NBSIR 77-1273

Directions to improve

Application of Systems

Approach to Fire Protection

Requirements for Buildings

Harold E. Nelson

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

Interim Report

(Sept. 1975 to Dec. 1978)

July 1977

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 77-1273

DIRECTIONS TO IMPROVE

APPLICATION OF SYSTEMS

APPROACH TO FIRE PROTECTION

REQUIREMENTS FOR BUILDINGS

Harold E. Nelson

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

Interim Report

(Sept. 1975 to Dec. 1976)

July 1977

U.S. DEPARTMENT OF COMMERCE. Juanita M. Kreps. Secretary

Dr. Sidney Harman, Under Secrotary

Jordan J. Baruch. Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

FOREWORD

This report is an interim product of a joint

effort of the Department of Health, Education,

and Welfare (HEW) and the National Bureau of

Standards (NBS) Center for Fire Research. The

Program is a five-year activity initiated in 1975

consisting of projects in the areas of decision

analysis studies, fire and smoke detection systems,

smoke movement and control, automatic extinguishment, and behavior of institutionalized populations

in fire situations.

This report is part of the decision analysis

study. ' In addition to giving a history of recent

developments in this area the report looks toward

the future and proposes a model of fire impact

based on a states transition concept leading to a plan for the derivation of a viable fire protection

engineering technology. Work in developing these

concepts further is a part of the Program and the

other efforts of the Center for Fire Research.

iii

CONTENTS

Page

FOREWORD iii

LIST OF FIGURES vi

Abstract 1

1. RECENT HISTORY OF THE DEVELOPMENT OF SYSTEM'S

APPROACH TO FIRE SAFETY IN THE UNITED STATES ... 2

2. SYSTEMS TO DESCRIBE FIRE GROWTH — PHYSICAL

MODELS/COMPUTER MODELS .... 5

3. SYSTEMS FOR THE ANALYSIS OF BUILDING FIRE SAFETY

DESIGN 7

4. DIRECTIONS ............ 9

5. REFERENCES 17

V
LIST OF FIGURES

Page

Figure 1. NBS Fault Tree — Control of the Building

Fire 18

Figure 2. Fire-Safety Systems, Seattle Federal

Building 19

Figure 3. General Services Administration FireSafety System Decision Tree 20

Figure 4. "AND" GATE 21

Figure 5. "OR" GATE 22

Figure 6. Overview Diagram — Fire Behavior Sequence 23

Figure 7. K Values — 1974 Harvard/Factory Mutuals

Test 24

Figure 8. Ignition-Initiation Phase 25

Figure 9. Initial-Item Development Phase 26

Figure 10. Intra-Room (Intra-Spacial) Development

Phase 27

Figure 11. Interspacial (Intra-Compartment)

Development Phase 28

Figure 12. Intra-Compartment Development Phase. ... 29

Figure 13. General Model 30

Figure 14. Matrix 31
DIRECTIONS TO IMPROVE APPLICATION OF SYSTEMS APPROACH

TO FIRE PROTECTION REQUIREMENTS FOR BUILDINGS

Harold E. Nelson

Abstract

This paper covers an examination of the

recent and ongoing work in the development of

systems' approaches for design of fire protection

in buildings, as carried out in the United States.

The scope of coverage includes:

(1) a brief review of the development of fire

safety systems’ approaches in the United States,

to the degree felt important to understanding

the current situation;

(2) an overview of the more extensive and pertinent fire growth systems' analysis approaches;

(3) a discussion of systems for the analysis of

building fire safety design directed at establishing building requirements;

(4) a review of the directions and activities now

underway to integrate the fire growth models

and the total building performance models into

a combined approach.

This paper proposes a model of fire and its

impact based on a " states-transition" concept.

The fire is viewed as two separate sequences

(Fire Behavior and Human Behavior) . Each sequence

consisting of connected realms of consistent

behavior. The concept views these sequences as

interrelating, with a distinct rate consistent

for each realm. The concept of " states-conditions

is also evaluated. A matrix relating the factors,

conditions, and development phase of fire is

presented. Finally, a plan for the derivation of

a viable fire protection engineering technology

is presented.

1
Key words: "And" gate; behavior; critical events;

decision; decision tree; dominant factors; episode;

event; fire; fire behavior; fire growth; fire

safety; human behavior; models; phase; probability;

rate constant; realm; sequence; state; statestransition; system's approach.

1. RECENT HISTORY OF THE DEVELOPMENT OF SYSTEM'S

APPROACH TO FIRE SAFETY IN THE UNITED STATES

It is worthwhile to briefly view the history of system's

development in fire safety in the United States. Of particular interest is that portion of the history that relates to

the use of event trees as a principal instrument in total

building fire safety performance analysis. The "success" or

decision type of event is a candidate alternative to the

current approaches used in building codes.

The event tree methodology has its technical antecedents

in reliability analysis and fault tree analysis. Both of

these approaches have been extensively examined in the United

States. An excellent review of the state-of-the-art at

varying levels of sophistication in reliability and fault

tree analysis is contained in the recent Society for Industrial and Applied Mathematics publication, "Reliability and

Fault Tree Analysis" [1]^.

The recent history of milestones in the application of

such systems' concepts to the determination of fire protection requirements for buildings can be chronicled approximately as follows:

A . International Conference on Firesafety in High-Rise

Buildings - Airlie, Virginia, April 12-16, 1971.

The report of this conference [2] strongly

emphasized the need for a total system's design

and management approach in transferring new

design and use concepts to the creation and

operation of modern high-rise buildings. The

conference report made a number of proposals

listing the general elements for such a system.

B. Seattle Federal Building . The Seattle Federal

Building was chosen by the General Services

Administration (GSA) to be used as an example

of potentials for engineered fire safety for

1 Numbers in brackets refer to the literature references

listed at the end of this paper.

2
high-rise buildings. The author, then Director

of Accident and Fire Prevention for the General

Services Administration, reviewed the proposed

design of the Seattle Building in consultation

with the design team and unilaterally selected

the fire safety requirements for that building.

This occurred in June 1971. While the items

selected were the best judgement of the writer

in terms of systematic approaches to fire safety

there was no system technique developed at that

time. The Seattle Federal Building can best be

considered as the father rather than the child

of system’s approach techniques.

C . Reconvened International Conference on Fire Safety

in High-Rise Buildings, Washington, D.C.,

October 5, 1971 . This conference was primarily important in two

aspects

:

1. A presentation entitled "A Method of Analysis

for Control of Building Fire" was delivered by

Mr. Irwin A. Benjamin, National Bureau of Standards.

Included in this presentation was a fault tree

event logic diagram considering the elements or

events essential to the control of the building

fire. This fault tree is reproduced as figure 1

attached to this paper.

2. The author presented a review of the fire safety

systems for the Seattle Federal Building. Fire

Protection elements were summarized in a fire safety

systems guide sheet which is included as figure 2.

Figures 1 and 2 constitute the first attempts to

make logical analysis of the total fire safety

systems in buildings.

D. GSA Decision Tree . A joint effort by NBS and GSA

(General Services Administration) developed a success tree aimed at determining the various

approaches available to achieving fire safety

objectives in buildings. This was then taken by

GSA through several revisions and generations.

The current version is attached as figure 3. This

is the basic reference document in the GSA goaloriented system's approach.

3
E. National Fire Protection Association (NFPA)

System's Committee . In 1972 the NFPA formed the

Committee on System's Concepts for Fire Protection

in Structures. This Committee using the background

for all the preceding items developed a success tree.

The current version of that success tree is available from the NFPA. The principle difference

between the GSA and the NFPA tree is in manner of

expression. The GSA tree generally uses a quasiAlgebraic approach that attempts to express the

subdivision of each event as functional elements of

that event. The NFPA tree expresses itself in terms

of cause and effect. At each gate in the NFPA tree,

an attempt has been made to assure the events below

the gate represent all causal elements of the event

above the gate.

F. GSA System's Approach . The General Services

Administration produced the "Interim Guide to Goal

Oriented Systems Approach to Building Fire Safety"

[3]

.

This was initially produced in 1972 and

published as a GSA internal criteria. As of this

time this is the only completely described analytical system for probabilistic evaluation of the

expected success in total performance of fire

safety in buildings.

G . Application of the GSA Goal-Oriented System to

Building Design . GSA has applied the goaloriented system's approach to several buildings

and has used the results to acquire the data base

of information as essential elements in making

design determinations. The level of confidence in

the system at this time, however, is such that the

system output can be considered an important input

but not a sole determiner of major design decisions.

Where the system's approach indicates a solution in

conflict with traditional (i.e., code type)

approaches, it is important that the conflict

be resolved on its technical merits rather than

any assumption of corrections inherent in either

approach. The largest single structure and most

extensive application of this has been to the

Atlanta Federal Building. This building has currently been designed though not yet built. In

1974 GSA published a report of the application of

the goal-oriented system to the Richard B. Russell

Court House and Federal Building now under construction in Atlanta, Georgia [4].

4
H. NFPA/Department of Housing and Urban Development

Study

.

In 1975 the U.S. Department of Housing and

Urban Development awarded a contract to the National

Fire Protection Association to undertake a study

of the application of system's analysis and the

success tree approach to residential types of

structures. This project is now underway. The

most significant potential of this project to date

is the work done by its subcontractor,

Mr. Ed Connelly, 0MNEM1I Incorporated, in the

modeling support for the study.

I . Recent Developments in System's Dynamics/States

Transition . The interplay of the participants in

all of the above activities has resulted in new

concepts. These generally relate to the conditions

that govern or dominate any state of fire development, the transition from state to state and the

interplay between the states and transition and

the actions of humans or the impact of fire protection measures. These are discussed in more

detail later in Section 4

.

2. SYSTEMS TO DESCRIBE FIRE, GROWTH

PHYSICAL MODELS/COMPUTER MODELS

At this time most of the inputs used by those working

with system's approach are the same as used in code application and fire insurance consideration. These consist

primarily of experience, data from individual tests, separate

research results, personal experience, and collected consensus

opinion. This imposes important constraint on the use of

current systems approach techniques due to the limited degree

of confidence that can be placed on the inputs into the system

related to fire growth factors. Several different deterministic types of fire growth concepts and fire growth models,

however, are currently being developed. One or more of

these may make a major contribution towards raising the

confidence level in total systems' approaches to the point

where it would be reasonable to use system's analysis as the

unilateral determinant of fire safety requirements.

A conceptual approach to evaluative fire growth has

been published under the title "Systems Analysis of Energy

Environment in Buildings" [5]. This study conceived fire in

a step-by-step growth process. Its principal value at this

time is in evaluating the various states and transitions

involved in fire growth.

5
Efforts have also been directed towards development of

empirical models to describe fire growth in more quantitative

terms. All of the major efforts in this area involve incremental finite analysis as the basis of the empirical approach.

Each of the three major contributions in this area has,

however, approached the problem of modeling a fire from a different perspective.

(1) Dr. John A. Rockett in 1968 [6] proposed a model

based on subdividing the entire volume of the building or

space into cubicle elements and undertaking an analysis of

interactions between and within the cubes. In an article

discussing the proposed model Dr. Rockett expressed the

significant problem as the volume of data necessary to be

handled. He expressed confidence in the ability of such a

system to handle gross action. However, he expected that

fine details about the course of a fire or the movement of

smoke will not be susceptible to such analysis for some

time. Dr. Rockett is not personally continuing to work-in

this area but others are using the programs he developed and

other aspects of his initial studies.

(2) A University of Dayton Research Institute team

with Mr. Jerry Reeves as principal investigator has developed

a computerized program for description of fire development

(unpublished) . In the UDRI approach the positions of all

elements in a space are described and the finite fire growth

analysis described as incremental spaces on the surfaces of

the combustible materials. This program was designed to

predict fire development in aircraft interiors and is predicated on spread along contiguous surfaces and transfer

across spaces separating such surfaces. The program input

is taken from rate of heat release of the exposed materials

with the test values measuring speed of flame propagation

horizontally, upward, and downward at varying levels of

incident flux. To date, the model has not been proof-tested

and has not yet been released for public view. Full-scale

tests of the system are to be made using aircraft cabin

burn-out tests in the near future.

(3) Messers Tom Waterman and Ronald Pape at the

Illinois Institute of Technology Research Institute working

on a grant from the Center for Fire Research at NBS have

proposed a system which they refer to as semistochastic. In

their approach, the space is described in terms of its

constituents with all fuels identified as boxes located in

this space. The input required is basically the rate of

heat release of the individual boxes as would occur in a free burning test situation. Using empirical energy input

data from numerous tests of furniture and fuel loads in

6
rooms and spaces, they have developed a computerized system.

This system interfaces this data with the impact of the

enclosing space, the separation of fuels, and other factors

to determine the time, intensity, and form of fire spread,

energy development, and combustion product development in

the room of fire origin. This program has been completed

and is now being reviewed by members of the staff of the

Center for Fire Research. Full-scale testing will be conducted at the NBS and the results will be correlated with

the model.

3. SYSTEMS FOR THE ANALYSIS OF BUILDING

FIRE SAFETY DESIGN

Current approaches to system's analysis for determining

building fire safety requirements are primarily based on the

decision-tree approach presented in the GSA document entitled

"Interim Guide to Goal Oriented Systems Approach to Building

Fire Safety" [3]

.

The use of a decision tree approach of this type provides the user with a unique capability to:

1. study and determine the organization of the various

"events" 2 that control or determine fire and the

response to fire;

2. establish the interrelationships between these

events, and the sequence in which the impact of

events must be considered; and

3. state the level of success or other measurements

of performance in a given situation.

All systems' approaches are (1) limited by the validity of

the data used and (2) require understanding of the meaning

of the statements of success or performance produced.

With these capabilities and limitations in mind, the

objective of the system's approach is to achieve a better and

more exact understanding of the degree of safety provided

The term "event" is used to describe any physical conditions,

use factors, activity, or action that can cause or control

fire, its effects, or the response to fire.

7
along with the ability to determine the impact of individual

events or the sensitivity of the system to change during

that event. In addition the system's approach will give:

1. a mechanism to allow design innovations and options

that best combine the necessary degree of safety

with all of the other building design features;

2. a basis to evaluate cost effectiveness where the

safety worth can be related to the cost, not simply

in terms of monetary differences, but in relation

to the actual safety impact per dollar invested;

and

3. a system whereby the responsible authorities, be

they code officials, underwriters, owners or others

can evaluate whether safety goals are being met

without having to review each specific design

requirement or variation.

The tree network is a diagrammatic means of showing a complete event/logic system that progressively subdivides

the problem into smaller and smaller elements to the level

at which the user wishes to make input into the system. The

tree arrangement assists in: (a) pointing out events which

must occur simultaneously or independently, (b) showing

which events can contribute most effectively to reaching a goal, and (c) expressing the choices or tradeoffs to insure

a satisfactory goal or objective level. The tree does not

within itself show the extent of conditionality or exclusivity. It does however provide a visual arrangement which

can assist the user in identifying where questions regarding

exclusivity or conditionality must be resolved.

In a decision tree, the levels of events are connected

by gates. There are two types of gates: the "and" gate

and the "or" gate. The type of gate used indicates the

relationship of the events below the gate to the success of

the events above the gate in the decision tree.

The location of an "and" gate between two levels of

events signifies that all of the events in the level immediately below the gate are necessary for achievement of the

success of the event above the gate. Exclusion of any

element directly connected to the lower side of an "and"

gate precludes success of the event above the gate. Therefore, the maximum probability of success of an event above

the "and" gate is limited to the lowest probability of

success of any event connected to it. Formula for determining the probability of success of achieving the goal

objective of an event above an "and" gate is shown in

figure 4

.

8
The location of an "or" gate between two levels of

events signifies an "and/or" relationship. In this case,

total inclusion of all of the events below the gate is

desirable, but not necessary, to achieve the goal of the

event above it. Exclusion of any event connected to the

lower side of an "or" gate does not preclude success of the

event above that gate. The probability of success of an

event above an "or" gate is always equal to or greater than

the highest probability of success of any of the events

connected to it.

Figure 5 provides graphic examples and formula for

determining the probability of success of achieving a goal

objective through an "or" gate.

Both the GSA and the NFPA decision trees are amenable

to the probabilistic approach upon which the GSA goaloriented system is based. These decision trees have been

extensively examined by groups interested in fire safety and

are felt to represent sound representations of the elements

that determine the course of fire development and growth and

its impact on people and the course of fire development and

growth and its impact on people and property. Other trees

could be developed that would be as effective. The actual

events in the tree are not individually important. It is

necessary however that any alternative tree seeking to

produce the same results follow the protocol of starting

from the same top event "Fire Safety Objective" and at each

step divide the entire universe of events as either an "and"

or an "or" function. At each gate the subordinate events

must sum to be the total universe of events that constituency add up to the event above the gate. If this is not

followed at an "and" gate the result will be failure to

protect against a potential system's failure. If an element

is omitted at an "or" gate the result will not reduce the

potential safety but would reduce the flexibility of choice

in the system by eliminating one or more alternatives.

4. DIRECTIONS

The goal-oriented systems' approaches have been valuable

in giving indications of the extent of the impact of fire.

They are currently limited in their ability to include rate

or time factors and in the lack of an adequate store of fire

protection engineering data. This lack of data forces the

system to use either engineering opinion or concensus

committee-type of decision for many of the most important

inputs. To overcome these limitations it is necessary to

find better linkages between applied fire protection and

scientific and/or empirical engineering data and to develop

9
I

a procedure which relates to fire growth. In addition, a better methodology is needed for interrelating human action

as it impacts either on the fire and its development or on

the safety of persons exposed to fire.

Recently, a combined concept has emerged. This resulted

from examinations of the various concepts on energy development, the system's approach, and data that is being developed

by current research. In this concept, both fire growth

modeling (part 2, above) and building fire safety design

systems' approaches (part 3, above) are combined into an

integrated system. The purpose of this new approach is to

provide a more complete base of knowledge by which rational

inputs can be made into a decision tree analysis.

This concept is based on the premises that:

1. Fire behavior and the behavior of persons involved

can be expressed as series of realms connected

together to form sequences.

2. The fire behavior and people behavior sequences are

separate, but can be (and often are) interacting

with each other. (A typical interaction is the

opening or closing of the door to a room that is

on f ire .

)

3. A sequence consists of individual periods of consistent behavior pattern, varying in length, and

beginning and ending with a critical event. These

periods of consistent behavior are called "realm"

when discussing fire behavior and "episodes"

when discussing human behavior. (The burning of

a chair might be a typical realm; if a second item

becomes involved or the room flashes over the rate

of burning will significantly change and a new

realm will exist.)

4. For each realm there is a "rate constant" which,

if identified, can describe the rate of change

during that realm. A change in the rate constant

constitutes a change in realm. (The chair described above either burns, releases energy, or

produces smoke at a consistent acceleration; if

the realm changes this rate of acceleration changes.)

5. At any instant in the combined fire behavior/human

behavior sequences there is one and only one value

for each behavioral property. These properties

are called "states conditions" and are identifiable and potentially quantifiable (e.g., the size

of the flame or rate of smoke production)

.

10
6 . There are potentially identifiable factors in the

decision tree events that control both the rate

constant within a realm, and the level of events

that determine the start and termination of a realm.

These factors are described by both the GSA and

NFPA trees; but , the individual dominance or proportional impact of a single factor is not directly

identifiable from the decision tree approach. In

terms of the sequence, a significant change in a dominant factor, its degree of dominance, or the

entry of new "dominant factors" will result in a change in the rate constant, and thereby a change

in realm. (A prime example of this occurs in the

transition through flashover. Prior to flashover

the fuel properties such as ignitability and fuel

arrangement dominate the fire development and

energy levels. After flashover the dominant

factors are the ventilation and the total amount

of available fuel.)

Fire Behavior Sequence . Figure 6 is a modification of the

overview design presented in reference [3]

.

This figure

presents the major sequences (or "phases") in fire development. The input arrowheads at the left of the figure indicate the necessity for the combination of energy in an

environment to have a fire start.

Energy as shown means the input or potential

ignition energy to start the fire sequence.

Environment describes the physical situation

consisting of fuel, geometry, construction,

ventilation, and general layout and arrangement as exists at the moment of introduction

of the energy source.

The development and spread of fire and fire energy through a facility is then divided into five basic phases each of which

will consist of one or more realms. The division of phases

is based on the expected types of dominant factors. These

are

:

1. The Ignition-Initiation Phase covers the period

from the entry of the potential ignition energy

to the point of self-sustained burning of one or

more items. In this phase, the development is

almost entirely dominated by: (1) the transfer of

energy from the ignition source to the target,

(2) the reaction to this energy by the target.

11
and (3) the critical ignition parameters of the

target material. The shape of the target and

the arrangement or geometry of the environment

have little to do with ignition or development

realms in this phase.

2. The Initial Item Development Phase is the second

phase and covers the development of fire from the

initiation of a self-sustained flame to the point

where the fire either terminates or extends to

one or more additional items. In this phase, not

only the basic physical properties of the material,

but also its shape and form, the spacing and

arrangement of other materials (second targets)

,

and the space configuration and ventilation begin

to play parts.

3. The Intra-Room Development Phase concentrates on the

spread of fire between items within a room or space

up to a point of fire termination of flashover in

a room. In this phase the additional elements of

radiation from the burning item or its flame, the

degree of separation between items, and other space

factors come into more important play.

4. The Interspatial Propagation Phase covers the

spread of fire from space to space through unprotected openings. In this phase, important factors

related to ventilation, transfer of combustion

products, convected energy, and radiated energy

dominate the basic fuel considerations more

important prior to flashover.

5. The Intercompartmental Spread Phase considers the

factors related to spread fire when a physical

barrier exists. Here the impact of total fire

severity on structural elements leading to building

collapse or ignition due to conduction of energy

are the most important and dominating considerations.

The arched lines in figure 6 going from phase to phase

are a schematic representation of the fact that it is not

necessary to totally progress through any phase before passing

through the next phase. In fact, the development conditions

necessary for a critical event may cause a jump to a next

phase or even skip an entire phase.
States Conditions — Fire Sequence . The "states conditions"

describe the state of the fire behavior at any instance in

the sequence. The fire development subsequent to any instant

is dependent upon the states conditions and the realm at that

instant; but is not dependent on the history of how that set

of conditions came to be.

The "states conditions" necessary to describe the fire

state at a given time are:

1. Fire Bed Location - Described in terms of the size

and location of the energy generator. It includes

both the basic burning area and the area away from

basic burning area where gaseous combustion is

taking place.

2. Energy Release - Expressed both in terms of the rate

of energy release at a given instant and the total

energy released in the course of the fire accumulated to that instant.

3. Pyrolysis Products - States in terms of concentrations and rate of change in concentrations. Covers

the non-energy releasing aspects of fire products

such as particulates, gases, vapors, be they toxic

or non-toxic, visible or non-visible. In the case

• of chemical products it also includes the rate of

subsequent change in the chemical products.

Rate Constant of Realm . Various research projects and tests

where rates of energy production or other reasonable measurements indicative of rates of energy or products production

have been taken indicate that under fire conditions the

energy release rate in a given realm varies at a constant

rate of acceleration. This rate constant is determined by

the reaction of the total fuel and environment conditions to

the fire energy input. The formula for each realm is the

same but there is a different factor (k) for each realm. The

definition of a realm is the period of fire development with a constant k. In terms of a single realm, the formula for the

energy release states conditions, is believed to be:

q

= rate of energy release

13
‘L

= <5 at

= <5 at

t = time

k = rate

any instant with a realm

another prior instant with the same realm

between i and n constant for the realm

As one test of this concept the data from the 1974 full room

burn conducted as part of the Harvard/Factory Mutuals home

fire tests was calculated using this formula. Figure 7 is

a plot of the values of k. This plot shows a marked consistency between the value of k and the observed realms in

the fire. The plot is superimposed with labels of the

observable realms.

Realms, Dominant Factors and Critical Events . Figures 8

through 12 have been developed covering the five phases shown

in figure 6. In each of these phases, the figure shows likel

realms, the expected dominant factors, and the critical event

expected within that phase. In no case is it expected that

all of the realms depicted will occur. In each case the first

critical event is the most likely entry into the realm and the

last critical event is the definition of an event that would

result in passing from the final realm in the phase into the

first realm of the next phase.

Human Behavior Sequence. The basic criterion for the protection of humans during fire is the avoidance of occupancy

of the same space at the same time by people and conditions

intolerable to people. In fire situations the fire effects

may be moving, or of consequence in only a very limited area.

The humans involved may or may not be mobile and their safety

may or may not be dependent on their actions.

Studies of the types of actions (episodes) involved in

human behavior in fire are relatively few and rudimentary in

nature. To date, however, they would indicate that the types

of actions can be classified as: investigate, flight, attack,

alarm, rescue, and no action. These are not in sequence and

the probability of any action is unknown. At this time the

state-of-the-art is simply one of recognizing the types of

episodes and searching for any indication of which factors

are dominant.

States Conditions — Human Behavior Sequence . Looking ahead

towards the time when more rational predictions on human

actions can be made, the only states condition necessary to

describe person or persons involved is:

14

>1

CO
Position - Expressed in terms of a vector that defines

not only the location of the person (s) but the rate and

direction of movement.

With this it is possible to visualize the expression of

the rate constant in terms of the formula:

d

n

“ d

i + ^

d^ = position at any instant within an episode

d. = position at another prior instant within the same

episode

t = time between i and n

j = rate constant for the episode

This can be seen as a linear formula versus the exponential

formula used for energy development. In addition, the nonphysical factor of human decision is visualized as an efficiency factor. Physically, no human can react faster than his

personal maximum speeds and cannot occupy less space than that

required by his body. In practice, however, these capabilities

can be reduced by the types of decision made.

General Model . Figure 13 is a general model of the human

behavior and fire behavior sequences. As indicated by this

model, fire behavior is looked upon as a series of independent realms connected by critical events while human behavior

is a series of independent episodes connected by decisions.

The two sequences influence each other with stimuli that flow

from the fire behavior sequence to the human behavior sequence

causing action or impacting on the well being of the humans.

The flow of stimuli is caused by the fire behavior sequence

and is proportional to it, but entirely separate from it. The

flow from the human behavior sequence to the fire sequence is

in the form of impacting actions. The type of impacting

action can be one countering the development of fire such as

fire attack activities or the closing of doors or other activities aimed at confining the fire or relieving its effects.

Impacting actions can also be detrimental to the restraint

of fire due to activities such as evacuees leaving doors open

or ineffective attempts at fire control activities that result

in further spread and development. Human behavior can also

progress through part or all of its sequence without impacting

in any way on the fire, such as where evacuation takes place

without any action that causes the fire to grow or be confined.

15
Figure 14 is a three-dimensional matrix interfacing

States Conditions, Phases (Realms) , and Dominant Factors

(Decision Tree Events) . The purpose of the matrix is to

direct and organize the knowledge base in fire science and

technology in a manner focused on specific realms, conditions,

or determinants. As the matrix inputs are developed, the

knowledge derivable from the fire science and technology can

be fed into a decision analysis system for determining building fire safety requirements, giving a significantly increased

level of confidence in the product.

A proposed program for this transition is:

1. the assembly and organization of the existing

knowledge base to identify the relationship of

the knowledge to each of the intersections in the

matrix, and to identify apparent knowledge voids;

2. the identification of the significant phenomenon

controlling the k factor or comparable constant

in each matrix block (realm) and the phenomenon

that can cause critical events resulting in a transition to another realm;

3. develop models for predicting the fire phenomena

and for the response of the facility, its contents,

and its occupants;

4. improve these models towards a complete system of

deterministic models covering all realms, and

critical events to complete all the connections

and interfaces possible through the expansion of

the general model, figure 14;

5. for each realm, episode, and critical event,

identify the impact (sensitivity) of each event

or group of events (branch) of the decision tree;

6. conduct parametric analyses of the models to

develop possible scenarios and their resulting

impact. Relate the probability of each scenario

to accident loss data. Enter these values into

the building fire safety design system.

Relevance to Decision Tree . In an analysis of the fire

behavior sequence the k factor provides a mechanism for the

understanding of fire development which provides an input to

the tree. The specific impact on each individual decision

tree event will be consistent through the course of a realm.

Some events on the tree will have major impact on the course

of fire in that realm, others lesser or no influence. For

example the specific fuel ignition characteristics in

16
combination with the ignition source dominate the course of

fire on the initial surface ignited and establish the realm.

The fire resistance of the structure plays no part in this

realm. Conversely in a fully involved room fire the structural fire resistance along with the ventilation and total

fuel mass are the principle control factors. In this realm

the ignitability or flame spread characteristics are of

insignificant impact. The decision tree, therefore, is a mechanism for describing all of the events that can influence

the achievement of the top event "Fire Safety Objectives"

during all possible realms of the fire. In an individual

realm it is normal for some of the events to have no significance .This potential relationship between the k factor and the

decision tree provides new mechanisms for understanding and

application of system's analysis. Since the k factor accounts

for fire growth in terms of time, it will be possible to interlock the life-safety aspect of the protection branch of the

decision tree to the control branch.

5 . REFERENCES

[1] Reliability and Fault Tree Analysis, Society for

Industrial and Applied Mathematics, Philadelphia, Pa.

(1975)

.

[2] International Conference on Fire Safety in High Rise

Buildings, held April 1971, Airlie House - Warrenton,

Va . , General Services Administration, Washington, D.C.

[3] Interim Guide to Goal-Oriented Systems Approach to

Building Fire Safety, from Appendix D, Building Fire

Safety Criteria (PBS P5920.9), General Services

Administration, Washington, D.C. (April 27, 1972).

[4] Fire Safety Systems - Richard B. Russell Courthouse

and Federal Office Building, Atlanta, Georgia.

General Services Administration, Washington, D.C.

(November 18, 1974).

[5] Nelson, H. E., Systems Analysis of the Energy

Environment in Buildings, Fire Tech. Vol. 8, No. 1,

National Fire Protection Association, Boston, Mass.

(1972) , pp. 53-66

.

[6] Rockett, John A., Objectives and Pitfalls in the

Simulation of Building Fire with a Computer, Fire

with a Computer, Fire Tech., National Fire Protection

Association, Boston, Mass. (Nov. 1969), pp. 311-321.

17

Til l:] I

1 f" 1 T 1 ~T .Linn ! i _ L_ JJ

FELATn‘£ T/ME 70 DETECT A‘J> INSTALLED ^

>

zo

o

o

zX

O

r

10

iiSSSSXSXi

Is

IX

> ^

r\

? \l Till!

K£L 1*0 L iTr

cove (t ao e

1

1 M M

T3 7*

$ o

«S P

- N

tO

t.Z

XJ ^ >;

* £ 0 5 ' •>

y! ^

b

TJ

•c

to $1

.

\

1 \ f r:

ll

I - *. rmii !i 1 1 1

.ri r i ;iii!! HI 11.1 Mi l

: 1

:

' "1

1 FH. msi»

nrr] i m ' 1 1

i i 'i. .i.nimiL unn1 nnrmnTT i i 1"'

l;fill!i!l iminr 11 * *;;ss ! 5 S S

*0 • r-SS

l i r Ms $ rrrrnTHTTI~TTTTJJM. miII I ITT ! 1 1 H 11 I IT

rn rnT1 ITTT1 IMII! H

1rrnII IThutj 11

’

£

X

J 1 **

j i





AND" GATE

In the success type of decision tree the "and" gate probability of

success in achieving the goal objective of element A is:

a. Where the events at the B level are independent.

= <pB

> <pb > 1 2

<PB

> N

b. Where the events at the B level are interdependent.

P

/

P

A

= (P

B

> (P

B

/P

B

> •• 1 2 1

(P

B

/P

B

& P

B

> N 1 2

Probability of success of subscripted element

Probability conditional on preceding element (s) ... read as "given.

An example of an "and" gate extracted from the GSA tree is shown on the

left below. Here the success of a barrier is dependent on the barrier

being complete. It is also equally dependent on maintaining its structural integrity if exposed to fire. And finally, it is dependent upon

thermal resistance in preventing the passage of ignition temperatures

to the unexposed of the wall.

On the right below an "and" gate is depicted in the form of a venn

diagram. The degree of success is equal to the degree of intersection

of all of the elements.

Figure 4

.

"AND”

21
"OR GATE

In the success type of decision tree the "or" gate probability of

success in achieving the goal objective of element A is:

a

.

b.

c

1 2 1 N 1 2 An "or" gate is a point of potential design trade-off. An example of

an "or" gate from the GSA tree is shown on the left, below. This

indicates the supportive interplay between suppression systems; the

built-in construction features; and the fire potential of the occupancy.

On the right below the "or" gate is depicted in the form of a venn diagram. The degree of success is equal to the union of success provided

by any of the elements.

Where the events at the B level are mutually exclusive.

pa

( v

+ <v

•••• + ( V

Where the events are not mutually exclusive but are independent.

P

A

- 1.00- (1-P ) (1-p ) U-pR ) b

n Where the events are not mutually exclusive and are interdependent

.

P A = 1.00 - (1-Pn ) (1-PD /P ) (1-P* /P* & P„ )

Figure 5. "OR" GATE

22
Figure

6.

Overview

Diagram

-

Fire

Behavior

Sequence
SPREAD

OVER

SURFACE

OF

BED

l_33S g_0l X M

LsJ

*3S

i—M

24

Figure

7.

K

Values

-

1974

Harvard/Factory

Mutuals

Test
COHZUJ

>»

«So

fj- o

CD

<c_J

u_©

O o

ss =? o ® — co

»—

«e£ 2= 25 O

SE L= cz 2= ^ CD £

>-o

<1

_ 00

CO

OZOI—CD

«=C o

CD

Si25 S

25 !~

CL, o

CD

— yj iy >Q S

CD

DC CD

22

<E *4 QZ“ >"

q:

ujo

«s

q ij-1 CO — CD

COo

Cl, Z

UJ

CZ cz

UJ 2;.

—J , CD

UJ I—

—

UJ

XX

co

«sUJ

CSC

UJ

DC

UJcc

Q_©

CO

CD

CO£o

CD

CD

32

s£

CD—!

CD

CD2:

•st. —1 3C u- O

h~ l

OZ 00 O =>

D_ CO

Cl. 2

CD

O

CO CD ©

25

Figure

8.

Ignition-Initiation

Phase
o

CO

I—zo

excd

UJs

>-o

«st UJ

f—

CO©

CD

^OX

SD UJ

CD t— —» UJ

co 2

u_ ex o UJ

cu o —

UJ CO “D x 3: o 0 9 9 9

00

DCOo

«£Z

«e2: oo

CO CO

UJ

V—

•a:

O

h— ZO

U_0

UJ0•sc u_

U_O

UJ0<=X u_

CD

UJCO

*=£

OUJ

CD

1—

CO

2D

CO

>-

CD5—

i.ii z CE z OX UJ 2D s S5 z 0 2D

CO 0 2D

CO

~J

UJ

€2? UJ 0

CD 0 0

h- 1—

O

OS CX UJ t—

•SC CD «r z CD <£

h-zUJ

22

5x

j—

ui

UJCO0

G_ >

CD

CD

UJ

>-CD

CD

UJ

<£

>—CO

UJCD

«£ 1 t—Z

CD 2D CX

X z 2; =) Eu UJ

O DO

O UJ UJ UJ CO CO D>

©

©©

©

©

© o

CO

UJo

U_

cos

a:UJ

OX

CD UJ

z: o

«t

O U_

«=£ DC

Jil =>

CE

QCO <£ ©

OX2D

co1

UJ

I—

<C

h”

CO

>-a

<c

UJ

hCO9

26

Figure

9.

Initial-Item

Development

Phase
intra-room

(INTRA-SPACIAL) DEVELOPMENT

H- v* — §=

ra UJ

{3

DC

UJ DC o UJ 09

>O

UJ UJ 39

00 00 z oo OO O

\— UJ «£ 39

2 U- U- o DC >- CO

UJ o O <9 UJ s U- «£

> _ u_ > 09 1 UJ s OS O UJ 1— u_

_J

«s£ o S =3

H- OO

39

CO

a

UJ

CO

c=> a. O

2 O s S DC <s

1 DC

i

| l— CD 09 O U- U_ 1

ce C3

LkJ h- ce X o

^ u- s o

(—” o

<£

93 oo

oso

@ • © © o

u. co

UJ i— UJ

H- 2 cS 2 UJ b— =£ o 2 CO

ela o UJ O DC

_J

>

o

>-a

=S

D3 1 9> UJ Q S H— < u_ OO

e ©

27

Figure

10.

Intra-Room

(Intra-Spacial

)

Development

Phase.
iNTERSPACIAL

(INTRACOMPARTMENT) 1 «£

ft ft o Cd

ft s_ O ^

ft

ftl =5

1— H- ft

CO

ft CD

LU

— Z CD S CD

— h— cas ftl «— 22 LU

MJ>

LU

X o UJ

Li.. z o = 5

£2 ft

ft 1—

CO «s£ “I ft

fto

ft

ftl 2*

Q 3 LU

—1 UJ

O

_J „ UJ CO —J CO ft >- ft

•X HO <£ ft* eS UJ ft CO

CD ” «S 1— CD h- CD s— <£ H— S £

CO LU

LU

Q

CO CD

UJ tfX LU l ft

ft

CD

©©

© • ©

CO >- ft ft >-

ft CD

O ftl ft o ft • CO 1 1 l ft H*

H— ftl ft ft LU UJ 22 CD

«s£ ftl ft ft LU ro 2D SE o o H— ft CD

ft

X H- LU

h

—

u LU COO CD «s ft —— UJ ftl ft

ft LU CO > ft ftl ao=»* CO LU

«r

Q CD UJ o gS C£j o O H—

ft r_5 ft ft ft.

Wr=a7 «3£ SS ft < z

«=^ 1 CD

X ft UJ

2E <S&m ft CD ftl CO >

CDO

©

©

©

©

©

© Z Z o o

cd

«c

fto

ft

ft. CD

«XCD

c£

ft. CD

ft

ft

CD

w ft

=«= UJ ^ >o — <r£ «z CO

ft ft 1 LU LU >-

ft 1 CD

CO UJ UJ «sl 2E CD CD ftl i UJ CD 1—

«c

O «3C CO

LUft

©©

© o

co<

C/5 O

ft

28 i

Figure

11.

Interspacial

(Intra-Compartment)

Development

Phase.
INTER

-COMPARTMENT

DEVELOPMENT

Q_CO

CO

COH

2C UJ>»o

o

s

o

COoo. z 2E UJ

CO X o O Z£ UJ

I— «t z 32 2£ IE

CO

ce CO CO

>- UJ UJ ce > 1— i— CO UJ > UJ

rctoce CO S

«st to

CO

CO o «£ UJ _J

U_ a 2 CO © © © ©

CO

CKo

ceUJ o<1

3S

«no

o

CO

co2

OS=>

COO U- O. Ou X UJ ce UJ S >- _J Kn.

ts rr, u_ id EE > o co cs ^ S _

2 o ee t? >-“ 0.0

_J C3 *" £V- e£ q; «=£ CD X

ca

tS" •e

c/> 2ZO

>-CO

ee

DCo

o

o

co —

r

ce £ co

UJ K ^

O

o

CO

e£C_

<=£ C_3

CO

CO

<ccc

22

UJ

COo

Q.X

Uj DC e£ O S =3 L|J a

I

I 1 I o

2Z

=0 — a co k ao< <£ _J uJ

CO O CO

zz.

I ©

> 2E

«=S UJ

CCCO© ®

oID

DC

UJ

CO

I

<=£ K— —

J

‘r" e~

DC r—

UJ <-- re o

s— o

I I

c/>

SSo

COz

2n_o

_!

co

<£

ce

CC QC

CO

ce

cc w UJ S •a.

r ^ HD ce u_

H- p

22 >UJO

oce

u_

ce=5 UJ CO

ID

ct

co 22 CO CO ce u. UJs

c_o

UJ

t—UJ

CD

UJ1—

ce

UJ

ceZDCO

CO

22

t—

UJ

UJ

*;»

t—

c/> ce O

UJ

ce

1 ce CD o •el CO o =0

DEVE oCO

CD

D_

C_

IDCO

Q_XUJ o<cce

COZ

3

i <£

u_ © © ©

29

Figure

12

.

Inter-Compartment

Development

Phase
30

Figure

13.

General

Model
X

•H

5-1 -Ps

Q)P3

•rH in

N BS-1 I4A (REV 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLIC ATION OK REPORT NO. NBSIR 77-1273

2. Gov't Accession

No.

3. Recipient’s Accession No.

4 . TITLE AND SUBTITLE

DIRECTIONS TO IMPROVE APPLICATION OF SYSTEMS

APPROACH TO FIRE PROTECTION REQUIREMENTS FOR

BUILDINGS

5. Publication Date July 1977

6. Performing Organization f ode

7* E. Nelson 8 . Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4920900

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as No. 9

13. Type of Report & Period Covered interim

Sept 75 - Dec. 76

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less [actual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) This paper covers an examination of the recent and ongoing work in the development c systems' approaches for design of fire protection in buildings, as carried out in the

United States. The scope of coverage includes:

(1) a brief review of the development of fire safety systems' approaches in the Unit

States, to the degree felt important to understanding the current situation;

(2) an overview of the more extensive and pertinent fire growth systems' analysis

approaches

;

(3) a discussion of systems for the analysis of building fire safety design directed

at establishing building requirements

;

(4) a review of the directions and activities now underway to integrate the fire gre

models and the total building performance models into a combined approach.

This paper proposes a model of fire and its impact based on a "states-transition"

concept. The fire is viewed as two separate sequences (Fire Behavior and Human Behavic

Each sequence consisting of connected realms of consistent behavior. The concept viev

these sequences as interrelating, with a distinct rate consistent for each realm. Tht

concept of "states-conditions" is also evaluated. A matrix relating the factors, con- ditions, and development phase of fire is presented. Finally, a plan for the derivat;

of a viable fire protection engineering technology is presented.

17. KEY WORDS (six to twelve entries; alphabetical order- capita/i ze only the first letter of the first key word unless a proper name; separated by semicolons) "And" gate; behavior; critical events; decision; decision tr« dominant factors; episode; event; fire; fire behavior; fire growth; fire safety;

human behavior; models; phase; probability; rate constant; realm; sequence; state;

states-transition; system's approach.

18. AVAILABILITY [ x' Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGE

[ 2

For Official Distribution. Do Not Release to NTIS

UNC.L ASSIFIED 38

Q 1 Order From Sup. of Doc., U.S. Government Printing Office Washington. D.C. 20402. SD Cat. No. Cl}

20. SECURITY CLASS

(THIS PAGE)

22. Price

[X] Order From National Technical Information Service (NTIS)

Springfield, Virginia 221M UNCLASSIFIED $4.00

USCOMM.DC 29C42-
1 ! '